(1) Field of the Invention
The invention relates to isolating dam gates from adjacent bodies of water, such that the gates may be worked oil in a dry environment. More specifically, the invention is directed to a bulkhead which may easily be assembled and moved into operative position and, after completion of work on the gate, may easily be disassembled and stored in a dry environment.
(2) Description of the Prior Art
Currently, large floating structures, known as "bulkheads" are used to facilitate maintenance and repair work on gates of dams. The bulkhead blocks the water from the gate by forming a wall which spans from pier to pier (on either side of the gate) in front of the gate and sets on a ledge beneath the gate. The bulkhead, when not in use, is moored in the body of water at a location removed from the gate. In use, the bulkhead is moved from its mooring to the dam and in front of the gate. The bulkhead is flooded to sink the bulkhead onto the ledge beneath the gate. After work on the gate is completed, the bulkhead is evacuated, floated, and moved to the next gate or to its mooring location.
Such bulkheads weight approximately 500,000 pounds and are infrequently used, typically about every 5-10 years. Thus, most of the time the bulkhead is simply moored in the body of water. Because of the size and weight of the bulkhead, it is not practical to haul the bulkhead out of the water for dry storage. Accordingly, corrosion is a constant problem (and, on occasion, vandalism) and maintenance and repair of such bulkheads, done in the floating state, is very expensive.
Some dams are designed to receive "stop logs", or wall-like elements which, when used in combination, form a barrier in front of the dam, similar to a bulkhead. The dams adapted to receive stop logs are provided with grooves which are adapted to receive a plurality of the stop logs to block off water from a gate. The stop logs, typically about fifty feet in length, require handling by a crane to set in place. When not in use, the stop logs are stored in a dry location. The transportable size leads to ease of repair and maintenance for stop logs. However, not all dams are adapted to receive stop logs, and having a crane at the dam gate of a dam which can receive stop logs is often problematic and requires a skilled crane operator.
Thus, there is a need for a bulkhead which can be floated into position, similar to current bulkheads, but which can be removed from the water and stored in a dry location.